Hi Usman, I'm From England & the sessions are different to Pakistan. But We do grow a lot of Petunias in UK.
I say its to early to get impatient with them. There growth should come on as the days become longer & temperature go's up a bit. Petunias Don't get flowering till late spring In England & Petunias are not available till almost May time here. Pakistan maybe a little different But I recon its still to early to expect much . Just give food, if compost is lacking & Feed/water, roots not foliage.

Feed every two weeks(mild liquid feed) I Hope they Give you a big show for you come summer
